Acid Base Titration part 2.pdf

Applications of Acid-Base/Neutralizatio Acid-Base/Neutralization n Titration https://www.youtube.com/watch?v=lHcBLp Kjeldahl Method for McS4M

Organic Nitrogen Determination •Step 1. Digestion •The sample is oxidized in hot, concentrated H 2SO4 and turns black… •To convert Carbon and Hydrogen to Hydrogen to CO2 and H 2 O •To convert Amides convert Amides and and Amines to Amines to NH 4+ •To convert . . . Azo, . Azo, Azoxy Azoxy and Nitro Group to N or its oxide

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Catalysts Potassium Sulfate (K 2 SO 4 ) – ) – increases the boiling point of sulfuric acid Mercuric Oxide (HgO) – (HgO) – increases the rate of reaction Selenious Acid (H 2 SeO 3 ) – ) – best catalyst

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Applications of Acid-Base/Neutralizatio Acid-Base/Neutralization n Titration Kjeldahl Method for Organic Nitrogen Determination •Step 2. Distillation •The oxidized solution is cooled and then treated withh NaOH to liberate ammonia gas:NH 4+ + HO-  NH3(g) + H2O Glass or Porcelain beads are added to avoid bumping







Applications of Acid-Base/Neutralizatio Acid-Base/Neutralization n Titration Kjeldahl Method for Organic Nitrogen Determination Step 3. Titration 1.Using an excess amount of HCl: NH 3 NH4Cl

+ HCl



The excess HCl is determined using a standard NaOH solution: HCl + NaOH NaCl +

2. Ammonia distilled is collected in a







Applications of Acid-Base/Neutralizatio Acid-Base/Neutralization n Titration Kjeldahl Method for Organic Nitrogen Determination •Percentage Protein in the Sample % protein = % N * f f= 5.70 (cereals) 6.25 (meat products) 6.38 (dairy products)







Kjeldahl Method 1. A 0.58 0.5843 43 g sampl sample e of a plan plantt food food pre prepar parati ation on was was analyzed for its content by the Kjeldahl method, the liberated NH 3 being collected in 50.00 mL of 0.1062 M HCl. The xc’ss acid required an 11.89 mL back titration with 0.0975 M NaOH. Express the result of this analysis in terms of %N and % (NH 4)2(SO4)







Two Titration/Double Indicator Method for Carbonate and Carbonate Mixtures Volume Relations in Carbonate Titrations

Constituents in the sample

For equal volume of sample

For single sample

N aO H

Vo-ph = Vo-mr

Vph-mr = 0

Na2CO3

Vo-ph = 1/2Vo-mr

Vo-ph = Vph-mr

NaHCO3

Vo-ph = 0; V o-mr >0

Vo-ph =0

NaOH, Na2CO3

Vo-ph > 1/2V o-mr

Vo-ph > Vph-mr

V

V

Na CO , NaHCO

< 1/2V

< V









[Applications [Applications of Neutralization Titrations] Two Titration/Double Indicator Method for Carbonate and Carbonate Mixtures







[Applications [Applications of Neutralization Titrations] Example: (First case)







[Applications [Applications of Neutralization Titrations] Solution: From the general relationship (1)







[Applications [Applications of Neutralization Titrations]







[Applications [Applications of Neutralization Titrations] Two Titration/Double Indicator Method for Carbonate and Carbonate Mixtures



























Acid Base Titration part 2.pdf

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